Alkyne insertion into cyclometallated pyrazole and imine complexes of iridium, rhodium and ruthenium; Relevance to catalytic formation of carbo- and heterocycles

Article abstract of DOI:10.1039/c0dt00280a

The cyclometallated complexes [MCl(CN)(ring)] (HCN = 2-phenylpyrazole, M = Ir, Rh ring = Cp*; M = Ru, ring = p-cymene) readily undergo insertion reactions with RCCR (R = CO₂Me, Ph) to give mono insertion products, the rhodium complex also reacts with PhCCH regiospecifically to give an analogous product. The products of the reactions of the cyclometallated imine complexes [MCl(C^N)Cp*] (HCN = PhCHNR, R = Ph, CH₂CH ₂OMe, Me; M = Ir, Rh) with PhCCPh depend on the substituent R; when R = CH₂CH₂OMe a monoinsertion is observed, however for R = Me the initial insertion product is unstable, undergoing reductive elimination with loss of the organic fragment, and for R = Ph no metal-containing product is isolated. With PhCCH the cyclometallated imine complexes can give mono or di-insertion products. The implications for catalytic synthesis of carbo- and heterocycles by a tandem C-H activation, alkyne insertion mechanism are discussed.

Full text of DOI:10.1039/c0dt00280a

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PAPER
www.rsc.org/dalton | Dalton Transactions
Alkyne insertion into cyclometallated pyrazole and imine complexes
of iridium, rhodium and ruthenium; relevance to catalytic formation
of carbo- and heterocycles†
Youcef Boutadla, David L. Davies,* Omar Al-Duaij, John Fawcett, Rachel C. Jones and Kuldip Singh
Received 9th April 2010, Accepted 25th May 2010
DOI: 10.1039/c0dt00280a
The cyclometallated complexes [MCl(CŸN)(ring)] (HCŸN = 2-phenylpyrazole, M = Ir, Rh ring = Cp*;
≡
M = Ru, ring = p-cymene) readily undergo insertion reactions with RC CR (R = CO2Me, Ph) to give
≡
mono insertion products, the rhodium complex also reacts with PhC CH regiospecifically to give an
analogous product. The products of the reactions of the cyclometallated imine complexes
Ÿ
Ÿ
=
≡
[MCl(C N)Cp*] (HC N = PhCH NR, R = Ph, CH2CH2OMe, Me; M = Ir, Rh) with PhC CPh
depend on the substituent R; when R = CH2CH2OMe a monoinsertion is observed, however for R =
Me the initial insertion product is unstable, undergoing reductive elimination with loss of the organic
≡
fragment, and for R = Ph no metal-containing product is isolated. With PhC CH the cyclometallated
imine complexes can give mono or di-insertion products. The implications for catalytic synthesis of
carbo- and heterocycles by a tandem C–H activation, alkyne insertion mechanism are discussed.
catalysed by [MCl2Cp*]2 (M = Ir, Rh) in which they propose
that cyclometallation at Cp*M followed by alkyne insertion into
the M–C bond are important steps in the catalytic cycle.10–12
Introduction
Cyclometallation reactions in which a C–H bond is converted
to an M–C bond have been known for decades. Recently there
has been renewed interest in these reactions because of the wide
applications of cyclometallated complexes.1 In 2003 we noted
that acetate-assisted cyclometallation of various N-donor groups
occurred under very mild conditions with [MCl2Cp*]2 (M = Ir,
Rh) or [RuCl2(p-cymene)]2.2 Subsequent studies by us3 and others4
have shown that these are ambiphilic metal ligand activations
(AMLA),5 involving an electrophilic metal centre with assistance
by hydrogen bonding to the free arm of a coordinated acetate.
Since our initial publication this AMLA methodology has also
been extended to other donor groups.6–8 Therefore, this method
constitutes a facile high yield route to a range of half sandwich
cyclometallated complexes and hence provides an opportunity to
study their reactivity.
In recent years there has been substantial progress in incor-
porating a C–H activation step, usually cyclometallation, and
subsequent C–C bond formation into catalytic cycles.9 Such
processes, may remove the need to prepare halogenated precursors
for further functionalisation, hence provide a cheaper and more
atom-economic methodology. Coupling a C–H bond activation
step with an alkyne or alkene insertion into the cyclometallated
M–C bond and subsequent reductive elimination is a potential
route to heterocyclic products. Miura and coworkers have recently
reported a number of reactions to form carbocycles or heterocycles
A
similar sequence is likely involved in Cp*Rh catalysed synthesis of
indoles13 and isoquinolines14 reported by Fagnou’s group. At the
moment very little is known about the scope of these reactions,
in terms of the directing groups that can be used in the initial
cyclometallation and the range of substituents that can be used on
the alkyne. In this regard studies of the cyclometallation reaction
and subsequent reactions of the cyclometallated complexes with
alkynes are important to understand selectivity and reactivity
issues in the catalytic processes.
The reactivity of half-sandwich cyclometallated complexes with
unsaturated substrates is, comparatively little studied. Early work
by Pfeffer et al. showed that arene ruthenium cyclometallated com-
plexes [RuCl(DMBA)(arene)] (DMBAH = dimethylbenzylamine)
would react with alkynes to form coordinated isoquinolinium
salts which could be liberated from the metal using copper salts
as oxidants.15 Recently Jones et al. showed that related Cp*Rh
and Cp*Ir cyclometallated imine and pyridine complexes undergo
alkyne insertion with DMAD (dimethylacetylene dicarboxylate);
oxidative coupling of the pyridine complex with CuCl2 generated
isoquinolinium salts via C–N reductive elimination, however
this only occurred for the rhodium complex not iridium.7 In
contrast Fagnou provided evidence to suggest that, in some cases
at least, C–N reductive elimination can occur before oxidation
by copper salts.14 Miura et al. have also reported examples
of C–C reductive elimination after alkyne insertion, to give
carbocycles.12
Department of Chemistry, University of Leicester, Leicester, U.K., LE1
7RH. E-mail: dld3@le.ac.uk
† Based on the presentation given at Dalton Discussion No. 12, 13–15th
September 2010, Durham University, UK.
‡ Electronic supplementary information (ESI) available: Figures showing
structures of 3b,c and Table of crystallographic data for 3b,c. CCDC
reference numbers 772790–772800. For ESI and crystallographic data in
CIF or other electronic format see DOI: 10.1039/c0dt00280a
It is clear from these studies that the nature of the directing
group, the metal, and the alkyne substituents can all have a major
impact on the outcome of the reactions. We recently reported
our studies of alkyne insertion reactions with cyclometallated
oxazolines.16 Here we extend those results to reactions of cyclomet-
allated pyrazoles and imines and comment on their relevance to
This journal is
The Royal Society of Chemistry 2010
Dalton Trans., 2010, 39, 10447–10457 | 10447
©

the catalytic formation of heterocycles reported by Miura10–12 and
Fagnou.13,14
has inserted into the M–C bond rather than the M–N bond,
to form a seven-membered ring, as found in related alkyne
insertions into cyclometallated imine, pyridine and oxazoline half-
sandwich complexes.7,16 However, no ring closure by C,N bond
formation has occurred, in contrast to observations by Pfeffer et al.
on reactions of alkynes with cyclometallated amine complexes
[RuCl(DMBA)(arene)].15 It is noticeable that the Cp* in 2a,b,
and the p-cymene in 2c, lie over the originally cyclometallated
phenyl rings consistent with the ring current effects discussed
above. The geometry around the metal is very similar in the three
complexes and to complexes formed by insertion of DMAD into
[MCl(CŸN)Cp*] (M = Rh, Ir HCŸN = phenylpyridine) reported
by Jones et al.7 The M—C bond length is slightly shorter than the
M—N in each complex. The chelate angles C(1)—M—N(1) for
the seven membered rings range from 83.35(16)◦ in 2c to 85.67(9)◦
in 2b which are considerably larger tha◦n those for five membered
rings in 1a–c [range 77.4(1) to 78.5(3) ].17 The formation of the
seven-membered ring also requires a non-planar arangement of
the phenyl and pyrazole rings. Thus in 2a–c the angle between
the mean least squares plane of the phenyl and pyrazole varies
between 51.35 (2b) and 54.52◦ (2c). whilst in the five-membered
ring◦precursors 1a–c the corresponding angle varies between only
3.42 (1c) and 5.05◦ (1b).17
Results and discussion
Complexes 1a–c were prepared by acetate assisted cyclometal-
lation of 2-phenylpyrazole with [MCl2Cp*]2 (M = Ir, Rh) or
[RuCl2(p-cymene)]2. Full characterisation of these products is
described elsewhere.17 The reactions of 1a–c with alkynes were
then investigated (Scheme 1).
Scheme 1
Reaction of 1a–c with DMAD in MeOH led to monoinsertion
products 2a–c in good yields. The 1H NMR spectra of 2a–c show
the expected signals for the cyclometallated phenylpyrazole and
two methoxy signals for the inequivalent CO2Me groups of the
alkyne. The Cp* signals in 2a,b occur at ca. d 1.3, about 0.3 ppm to
higher field than the corresponding starting complexes. This can be
explained by a ring-current effect of the Cp* lying over the original
cyclometallated phenyl ring of the phenylpyrazole (see X ray
structure below). Similar ring current effects have been observed
for cyclometallated bisoxazoline benzene complexes,18 and related
complexes formed by alkyne insertion into Cp*M cyclometallated
≡
Similar reactions of 1a–c with PhC CPh in MeOH proceeded
in 1–3 h, to give products 3a–c in moderate to good yields. As
found for 2a,b, the 1H NMR spectra of 3a,b show the Cp* signals
approximately 0.30 ppm upfield compared to 1a,b as expected for
the seven-membered ring insertion product. The pyrazole signals
1
are at similar chemical shifts to those observed for 2a,b. The H
NMR spectrum of ruthenium complex 3c is similar to those of
3a,b except with signals for a p-cymene replacing those for Cp*.
Notably, the isopropyl group gives rise to two doublets (at d
1.08 and 1.23) and the four aromatic protons of the p-cymene
are also inequivalent, giving four doublets of doublets between
d 3.48 and 5.54, again showing upfield shifts (0.01 to 1.59 ppm)
in comparison to the starting complex 1c due to the ring current
effect described above. These data are also consistent with the
metal centre being chiral and epimerisation being slow on the
NMR timescale. The 13C NMR spectra of 3a–c show the expected
number of C–H and quaternary carbons, the metallated carbons
(C11) being observed between 15 and 6 ppm to higher field than
in 2a–c.
1
complexes.7,16 The H NMR spectrum of 2c also shows evidence
for a ring current affecting the four aromatic protons of p-cymene
which are 0.03–0.95 ppm upfield from the corresponding signals in
1c. The inequivalence of these four aromatic protons is consistent
with the metal centre being chiral and epimerisation being slow
on the NMR timescale.
Complexes 2a,b,c have been characterised by X-ray crystal-
lography and the structures are shown in Fig. 1 with selected
bond distances and angles. The structures confirm that the alkyne
Fig. 1 Molecular structure and atom numbering scheme for (a) 2a, (b) 2b, (c) 2c with 50% displacement ellipsoids, all H atoms are omitted for clarity.
◦
˚
Selected bond distances (A) and angles ( ) For 2a: Ir—N(1) 2.086(4), Ir—C(1) 2.050(5), Ir—Cl(1) 2.4183(12), C(1)—Ir—N(1) 85.08(16), C(1)—Ir—Cl(1)
88.51(13), N(1)—Ir—Cl(1) 86.84(11). For 2b: Rh—C(1) 2.040(3), Rh—N(1) 2.093(2), Rh—Cl(1) 2.4131(7), C(1)—Rh—N(1) 85.67(9), C(1)—Rh—Cl(1)
89.92(8), N(1)—Rh—Cl(1) 88.61(6). For 2c: Ru—C(1) 2.070(4), Ru—N(1) 2.097(4), Ru—Cl(1) 2.4183(17), C(1)—Ru—N(1) 83.35(16), C(1)—Ru—Cl(1)
89.37(14), N(1)—Ru—Cl(1) 85.94(11).
10448 | Dalton Trans., 2010, 39, 10447–10457
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The Royal Society of Chemistry 2010
©

Complexes 3a–c were also characterised by X-ray crystallog-
raphy and the structure of 3a is shown in Fig. 2 with selected
bond distances and angles. The structures of 3b and 3c are in
the supplementary material,‡ 3c has two molecules in the unit
cell and the Ru—C and Ru—N bond lengths vary in the two
molecules therefore bond lengths and angles are not discussed
below. Complexes 3a–c have similar structures to 2a–c and confirm
that the alkyne has inserted into the M—C bond rather than the
M—N bond, to form a seven-membered ring. The M—C bond
on the exact precursor and reaction conditions used.16 Hence the
≡
reaction of 1a,b with PhC CH was attempted.
≡
The reaction of Ir complex 1a with PhC CH in MeOH was
monitored by ES-MS and after 5 min, three signals were observed
at m/z 471, 573 and 675 which were assigned as [1a – Cl], [1a –
Cl + PhCCH] and [1a – Cl +2 PhCCH] respectively. The reaction
appears to give a mixture of mono and diinsertion products with
the second insertion occurring at a similar rate to the first one, so
that it is not possible to get clean conversion into the monoinserted
product. This is similar to what we found with an oxazoline
˚
lengths of 3a,b [2.069(6) and 2.061(7) A respectively] are shorter
than the M—N distances [2.088(5) and 2.096(6) A respectively]
complex.16 Addition of another equivalent of PhC CH led to
˚
≡
as found in 2a,b. However the M—C bond lengths of 3a,b are
longer than those of 2a,b whilst the M—N bond lengths are
unchanged. There are some small changes in the bond angles of
3a,b compared to 2a,b, the chelate angles decrease slightly while
the C(1)—M—Cl(1) angles increase slightly. This is presumably
due to the increased size of the phenyl substituent on C(1) in
3a,b compared with CO2Me in 2a,b. As found in 2a–c the phenyl
and pyrazole are not coplanar, the angles between the planes of
the pyrazole and original cyclometallated phenyl are 52.66◦ and
45.55◦ in 3a and 3b respectively.
more of the diinsertion product but still gave a mixture which we
were unable to separate.
≡
The corresponding reaction of PhC CH with 1b was complete
after 2 h; the ES-MS showed only one product peak at m/z
483 [1b – Cl + PhCCH]. This suggests that the first and the
second insertions are slower for rhodium than iridium, such
1
that the monoinserted product can be isolated. The H NMR
spectrum shows one set of signals with a 1 : 1 : 1 ratio of Cp* to
≡
the cyclometallated phenylpyrazole and PhC CH which suggests
only one regioisomer was obtained. The Cp* signal is observed
upfield from 1b at d 1.30, (c.f. d 1.35 in 3b). In the 13C NMR
spectrum, the expected number of quaternary and C–H carbons
≡
for one insertion of PhC CH is seen. The metallated carbon is
easily identified due to coupling with rhodium and is observed as
a doublet (J 125 Hz) at d 178.64. A DEPT spectrum showed that
the metallated C is a quaternary carbon which allows us to assign
the product as 4b having the phenyl substituent, rather than the
hydrogen, next to the metal. This regioselectivity is identical to
that observed for a Cp*Ir cyclometallated oxazoline complex.16
≡
The reaction of PhC CH with cycloruthenated complex 1c was
also investigated. After 1 h the ES-MS showed one peak at m/z
1
481 [1c – Cl + PhCCH], however the H NMR spectrum of this
sample showed three sets of p-cymene signals, one of which was
assigned to the starting complex. To try to convert more of the
≡
starting complex into product another equivalent of PhC CH was
added to the NMR sample. Unfortunately, instead of leading to
more conversion, decomposition occurred, the 1H NMR spectrum
showed broad signals and liberation of free p-cymene.
Fig. 2 Molecular structure and atom numbering scheme for 3a with
50% displacement ellipsoids, all H atoms are omitted for clarity. Selected
◦
In none of the above reactions does C,N bond formation occur
spontaneously in the alkyne insertion products 2a–c, 3a–c or
4b. Jones showed that with pyridine or an imine as a directing
group for the initial cyclometallation, oxidation of the alkyne
insertion products with copper(II) salts can induce C,N bond
formation.7 Reaction of 2b with Cu(OAc)2 was attempted but at
room temperature there was no reaction. This is not surprising
since no C,N bond formation is observed by Miura in the use of
pyrazole as a directing group in catalytic synthesis of naphthalenes
and these reactions occur at 80 ◦C.12
˚
bond distances (A) and angles ( ): Ir—N(1) 2.088(5), Ir—C(1) 2.069(6),
Ir—Cl(1) 2.4254(15), C(1)—Ir—N(1) 82.9(2), C(1)—Ir—Cl(1) 89.67(16),
N(1)—Ir—Cl(1) 86.45(14).
The cyclometalltion of 2-phenylpyrazole to form 1a–c and
subsequent reaction of these complexes with disubstituted alkynes
to form complexes 2 and 3 demonstrates that the first two steps
of the mechanism postulated by Miura for catalytic formation
of naphthylazoles, namely C–H activation and alkyne insertion,12
are entirely feasible. (Note, the catalysis occurs at 80 ◦C whilst
the cyclometallation and alkyne insertion both occur at room
temperature.)
Miura’s catalytic reactions all involve disubstituted alkynes.
Indeed, there are very few reported cases of alkyne insertions
involving monosubstituted alkynes.19 The only examples of stoi-
chiometric reactions of a half-sandwich cyclometallated complex
with terminal alkynes are with [CoI(DMBA)(Cp)] which only
reacts with terminal alkynes,20 and our results for a Cp*Ir
To investigate further the effects of the donor group on reactivity
we have studied some reactions of cyclometallated imines (Scheme
2). As we found for half-sandwich cyclometallated oxazoline com-
plexes, and as observed previously for palladium complexes,21,22
reactions with alkynes were facilitated by substituting the chloride
in the starting complexes with acetonitrile to provide cationic
complexes.16 Stirring complexes 5a,b or 6a overnight in acetonitrile
in the presence of KPF6 gave cationic complexes 7a,b and 8a
1
≡
cyclometallated oxazoline complex which reacts with PhC CH
respectively. The H NMR spectra show, in addition to signals
to give either a monoinserted product or a diinsertion depending
for the cyclometallated ligand and Cp*, a singlet integrating to
This journal is
The Royal Society of Chemistry 2010
Dalton Trans., 2010, 39, 10447–10457 | 10449
©

Fig. 4 Molecular structure and atom numbering scheme for the cation
of 8a with 50% displacement ellipsoids, all H◦atoms are omitted for
˚
clarity. Selected bond distances (A) and angles ( ): Ir(1)—N(2) 2.044(3),
Scheme 2
Ir(1)—C(1) 2.048(3), Ir(1)—N(1) 2.095(2), N(2)—Ir(1)—C(1) 87.57(11),
N(2)—Ir(1)—N(1) 92.29(10), C(1)—Ir(1)—N(1) 77.52(11).
3 protons at d 2.36, 2.23 and 2.49 for 7a,b and 8a respectively
assigned to coordinated NCMe, (free NCMe is observed at d
2.00). The CH2O protons of 7a,b give rise to two multiplets, the
inequivalence, suggesting that epimerisation at the metal is slow on
the NMR timescale unlike an analogous iridium cyclometallated
oxazoline complex which was fluxional on the NMR timescale.16
Complexes 7b and 8a were characterised by X-ray crystal-
lography and the structures are shown in Fig. 3 and 4 respec-
tively with selected bond distances and angles. The complexes
adopt the expected pseudo-octahedral structure with the Cp*
ligand occupying three facial coordination sites of the metal
and confirms the coordination of NCMe. As found in other
cyclometallated complexes,2,8 both complexes show two long
bonds to an sp2 rather than an sp nitrogen. The phenyl substituent
on nitrogen in 8a is rotated out of the plane of the cyclometallated
fragment (dihedral angle C(7)—N(1)—C(8)—C(9) = 122.8◦) and
is approximately parallel to the Cp* (angle between least squares
planes = 6.4◦).
Reactions of the cationic iridium and rhodium imine complexes,
≡
7a and 7b respectively, with PhC CPh were investigated. The
reactions were carried out at room temperature in CH2Cl2 and were
monitored by ES-MS and in each case only one peak was observed,
at m/z 668 and 578 respectively corresponding to replacement of
1
≡
MeCN by PhC CPh. The H NMR spectra of the products, each
≡
show a 1 : 1 : 1 ratio of the Cp*, the imine ligand and PhC CPh,
˚
˚
[2.240(3) to 2.273(3) A] and three short [2.138(3) to 2.172(3) A]
M—C bonds to the Cp*, with the longer ones approximately
trans to the metallated carbon. The M—N(imine) bond lengths
but no peaks due to coordinated NCMe are observed. In each
complex, the Cp* is observed, 0.35 ppm upfield from the starting
cationic complex, at ca. d 1.38 suggesting a ring-current effect
of an alkyne-insertion product. The other notable shift is that of
the OMe signals which are observed at d 2.48 and 2.35 for 7a
and 7b respectively, more than 0.86 ppm upfield from the starting
materials. These large shifts are in the opposite direction to that
expected for coordination of the OMe to the metal centre and are
again typical of ring-current effects. If after insertion of alkyne
coordination of the OMe occurs it places the methyl in the vicinity
of one of the Ph groups of the alkyne. Similar ring-current effects
were seen on coordination of the OMe in Pd(PPh3) complexes of
this imine.23 Hence the complexes are identified as 9a,b containing
a tridentate C,N,O ligand. For both 9a and 9b, the NCH2 and
CH2O protons are observed as inequivalent multiplets, consistent
with the chiral centre at the metal, and that epimerisation at the
metal is slow on the NMR timescale.
˚
[2.090(3) and 2.095(2) A] in 7b and 8a are longer than the M—
˚
N(NCMe) [2.069(3) and 2.044(3) A respectively] consistent with
The structure of 9a has been determined by X-ray crystallogra-
phy and is shown in Fig. 5 with selected bond lengths and angles.
The structure confirms that the insertion of the alkyne into the Ir–
C bond has resulted in the formation of a seven-membered ring
and coordination of the OMe has formed a five-membered ring.
The C(12)—Ir(1)—N(1) chelate bite angle [84.6(2)◦] is larger than
that for the N(1)—Ir(1)—O(1) angle [75.3(2)◦], which is expected
because of the larger chelate ring size.
Fig. 3 Molecular structure and atom numbering scheme for the cation
of 7b with 50% displacement ellipsoids, all H atoms are omitted for
◦
˚
clarity. Selected bond distances (A) and angles ( ): Rh—C(1) 2.032(3),
≡
Reaction of the phenyl-substituted imine 8a with PhC CPh
was tested since this does not have a pendant OMe group able to
Rh—N(1) 2.090(3), Rh—N(2) 2.069(3), C(1)—Rh—N(1) 78.54(11),
C(1)—Rh—N(2) 83.80(11), N(1)—Rh—N(2) 89.74(10).
10450 | Dalton Trans., 2010, 39, 10447–10457
This journal is
The Royal Society of Chemistry 2010
©

has been reduced to an amine. The product can be viewed as
≡
having been formed by insertion of PhC CPh into the M–C bond
of 8a and then ring closure between the new metallated carbon
and the imine carbon (i.e C—C bond formation) and protonation
at the nitrogen. Miura has reported catalytic formation of imino
indenes (formally dehydrogenation of 10) using [Cp*RhCl2]2 as a
catalyst precursor.10 This is in contrast to reductive elimination
by C–N bond formation as observed by Fagnou in formation
of isoquinolines using the corresponding NtBu imine complex of
rhodium.14 Notably in that case the t-butyl substituent on the
imine nitrogen is lost during the catalysis. Hence, it appears that
≡
the product of the reaction of PhC CPh with cyclometallated
imine complexes of Cp*M (M = Ir, Rh) depends crucially on the
substituent on the imine.10 The outcome of alkyne insertions into
palladium cyclometallated imine complexes was similarly found to
depend on the substituent on the imine, though no indenes were
found in those cases.22
Fig. 5 Molecular structure and atom numbering scheme for the cation
of 9a with 50% displacement ellipsoids, all H atoms are omitted
for clarity. Selected bond distances (A) and angles ( ): Ir(1)—C(12)
2.018(7), Ir(1)—N(1) 2.062(5), Ir(1)—O(1) 2.274(5), C(12)—Ir(1)—
N(1) 84.6(2), C(12)—Ir(1)—N(1) 84.6(2), N(1)—Ir(1)—O(1) 75.3(2),
C(12)—Ir(1)—O(1) 89.3(2).
◦
˚
We have also investigated the reaction of iridium complexes
≡
7a and 8a with PhC CH (Scheme 3). The reaction of 7a with
≡
PhC CH in 1 : 1 ratio in CH2Cl2 was monitored by ES-MS. After
4 h two major ions were observed at m/z 592 and 490 assigned
to a monoinsertion product and starting material respectively.
After 7 h a further peak was observed at m/z 694 assigned to
a diinsertion product. Thus the reaction appears to give a mixture
of mono insertion and diinsertion with the second insertion
occuring at a similar rate to the first one, as observed for the
cyclometallated pyrazole complex 1a discussed above. Therefore,
stabilise the insertion product. The reaction was monitored by ES
mass spectrometry, only an ion at m/z 358 was observed and there
was no evidence for the expected insertion product. The reaction
was worked up to give a light brown hexane soluble fraction and
a deep brown insoluble fraction, unfortunately nothing could be
1
isolated from the latter. The H NMR spectrum of the hexane
≡
the reaction was repeated using two equivalents of PhC CH. The
1H NMR spectrum of the crude product showed only one species
present with no signal for NCMe and the integration showing the
incorporation of two equivalents of alkyne, this was confirmed by
the FAB mass spectrum which showed an ion at m/z 694. The
Cp* resonance occurs at d 1.69, similar to that, d 1.75, in 7a,
suggesting that there is no ring-current effect in this case. Two
singlets due to the alkyne protons are observed at d 6.06 and 6.72,
with the corresponding carbon signals at at d 48.45 and 121.18
respectively, and the NCH2 protons give rise to two multiplets at
d 3.93 and 4.13; consistent with a chiral metal centre and slow
epimerisation relative to the NMR timescale. The spectroscopic
data is not able to unambiguously identify the product, fortunately,
soluble fraction was rather uninformative showing a broad peak
integrating to 1H at d 3.90 and a sharp 1H singlet at d 5.65 and
multiplets integrating to 19H in the aromatic region. Fortunately,
crystals suitable for X-ray diffraction were obtained and this
allowed identification of the compound as amino indene 10, the
structure is shown in Fig. 6 with selected bond distances. The
same compound, 10, was also formed in the reaction of 6b with
≡
PhC CPh, again unfortunately no metal-containing product was
characterised.
Fig. 6 Molecular structure and atom numbering scheme for 10 with
˚
50% displacement ellipsoids. Selected bond distances (A): C(1)—C(5)
1.503(5), C(1)—C(2) 1.513(5), C(2)—C(3) 1.354(5), C(3)—C(4) 1.486(5),
C(4)—C(5) 1.394(5), N(1)—C(10) 1.371(4), N(1)—C(1) 1.428(4).
The structure shows an amino indene; the C(1)—N(1) bond
˚
length [1.428(4) A] is typical of a single bond showing the imine
Scheme 3
This journal is The Royal Society of Chemistry 2010
Dalton Trans., 2010, 39, 10447–10457 | 10451
©

recrystallisation from dichloromethane–hexane gave X-ray quality
crystals. The structure confirmed the formation of the diinsertion
product 11a. The crystal structure of this complex is shown in
Fig. 7, with selected bond distances and angles.
efficient starting from NMe imines than with the NtBu complex
(8% versus 80% yield).14
≡
The reaction of 13b with PhC CPh in MeOH was attempted.
After 5 min the ES-MS spectrum showed three signals at m/z
356 [13b – Cl], 397 [13b – Cl + MeCN] and 534 [13b – Cl +
PhCCPh]. After 45 min a precipitate was formed, ES-MS and
FAB mass spectra of the solid showed a peak at m/z 296, implying
C–N bond reductive elimination to form an isoquinolinium salt
and dissociation from the metal have taken place.24 The 1H NMR
spectrum of the precipitate showed a mixture of products with two
broad and intense signals in the Cp* region at d 1.58 and 1.55 and
one set of signals for the new cyclometallated ligand with an NMe
signal at d 3.36, however the Cp* and NMe signals are no longer
in a 1 : 1 ratio. Unfortunately, we were unable to isolate any pure
compounds by crystallisation or chromatography.
≡
The corresponding reaction of 13b with PhC CH was also
examined. After 5 min the ES-MS spectrum showed three signals
at m/z 356 [13b - Cl], 397 [13b - Cl + MeCN) and 458 [13b -
Cl + PhCCH], a solid precipitated after 30 min and after 45 min
only one peak was observed at m/z 458. The 1H NMR spectrum
of the solid showed one set of signals consistent with only one
regioisomer of the expected monoinsertion product 14b. The Cp*
is observed at d 1.35, 0.34 ppm upfield from 13b as observed for
the other alkyne insertion products discussed above. Fortunately
the crystals which deposit from solution were suitable for X-ray
diffraction and this confirmed the identity of the complex as 14b.
The structure of 14b is shown in Fig. 8 with selected bond distances
and angles.
Fig. 7 Molecular structure and atom numbering scheme for the cation
of 11a with 50% displacement ellipsoids, only the ipso carbon C(21) of
the terminal phenyl substituent is shown and all◦H atoms are omitted for
˚
clarity. Selected bond distances (A) and angles ( ): Ir(1)—C(19) 2.087(4),
Ir(1)—N(1) 2.097(4), Ir(1)—C(11) 2.159(4), Ir(1)—C(12) 2.172(4),
N(1)—C(4) 1.284(5), C(10)—C(11) 1.482(6), C(11)—C(12) 1.464(6),
C(12)—C(19) 1.417(6), N(1)—Ir(1)—C(11) 90.20(16).
5
The structure shows the expected h -Cp* and an eight-
membered metallacycle formed by insertion of two molecules of
≡
PhC CH into the M—C bond of 7a. The new ligand coordinates
through the imine nitrogen and via three adjacent carbon atoms
3
in a h -allyl type interaction. This is analogous to the diinsertion
product from a cyclometallated oxazoline.16 The bonding of the
3
h -allyl is slightly asymmetric with the Ir—C(19) bond length
˚
[2.087(4) A] being shorter than the bonds to C(11) and C(12)
˚
[2.159(4) and 2.172(4) A respectively]. The allyl is oriented with
the central carbon atom (12) and its phenyl substituent C(13)—
C(18) pointing up towards the Cp*, this is in contrast to the anti
isomer we reported for the oxazoline analogue. The C(19)—C(20)
˚
distance, [1.326(6) A], is typical of a double bond and is much
˚
shorter than the C(11)—C(12) bond length [1.464(6) A] which is
now part of the h -allyl.
3
A similar reaction was attempted with the NPh-imine complex
1
6a. The H NMR spectrum of the crude product showed more
Fig. 8 Molecular structure and atom numbering scheme for 14b with 50%
than one Cp* signal, however after filtering the mixture through
displacement ellipsoids, all H atoms are omitted for clarity. Selected bond
1
◦
silica only one product was isolated. The H NMR spectrum of
˚
distances (A) and angles ( ): Rh(1)—C(9) 2.029(7), Rh(1)—N(1) 2.059(6),
the product shows a 1 : 1 : 2 ratio of the Cp*, imine and alkyne
ligands as expected for the formation of a diinsertion product. The
Cp* is observed at d 1.51, similar to that, d 1.47, in the starting
chloride complex 6a. Two singlets are observed at d 5.20 and 6.72
assigned to (H7) and (H10) respectively. The FAB mass spectrum
showed a molecular ion at m/z 712, confirming the presence of
Rh(1)—Cl(1) 2.4130(19), C(8)—C(9) 1.365(9), C(9)—Rh(1)—N(1)
87.6(3), C(9)—Rh(1)—Cl(1) 90.0(2), N(1)—Rh(1)—Cl(1) 89.63(16).
Complex 14b shows the expected 7-membered ring formed by
insertion of the alkyne and that reductive elimination by C—N
or C—C bond formation has not occurred yet. The structure
confirms that the isomer formed has the phenyl group on the
carbon attached to the metal with the hydrogen next to the original
cyclometallated phenyl, the same as for 4b discussed above.
≡
two molecules of PhC CH. The X-ray structure confirmed the
product as 12a, however, the data was not of sufficient quality to
merit discussion of the bond lengths and angles.
˚
As mentioned above, the products of the reactions of cyclomet-
The M—C and M—N bond lengths [2.029(7) and 2.059(6) A,
≡
allated imines with PhC CPh seem to depend on the imine
respectively] are slightly shorter than the corresponding distances
˚
≡
substituent. Hence, we decided to study further reactions of alkyl
substituted imines. Jones has previously reported that the reactions
of NMe substituted imine complexes 13a,b with DMAD give the
simple monoinsertion products.7 Fagnou, in a footnote, suggests
that [RhCl2Cp*]2 catalysed synthesis of isoquinolines is much less
[2.061(7) and 2.096(6) A, respectively] in the PhC CPh pyrazole
insertion product 3b described above, whilst the chelate angle C—
M—N is larger [87.6(3) and 84.5(2)◦ in 14b and 3b, respectively].
However 14b is not stable in solution, after a few hours in
CDCl3, a further reaction occurs and a new set of signals is
10452 | Dalton Trans., 2010, 39, 10447–10457
This journal is
The Royal Society of Chemistry 2010
©

1
observed in the H NMR spectrum. The Cp* signal is observed
1a–c,17 5a,b 6a,b2 and 13a,b7 which were prepared by literature
at d 1.63 a downfield shift of 0.30 ppm suggesting there is
no longer a 7-membered chelate ring present, and the NMe
signal is observed at d 3.43. The FAB mass spectrum at this
stage shows the same peak at m/z 458 (see above) and a new
peak at m/z 220 consistent with reductive elimination of the
C,N bond and formation of an isoquinolinium salt. Unfortu-
nately, further purification by crystallisation or chromatography
failed.
methods.
Preparation of (2a)
A mixture of [IrCl(phenylpyrazole)Cp*] 1a (50 mg, 0.099 mmol)
and DMAD (17 mg, 0.12 mmol) in MeOH (5 mL) was stirred
for 1 h at RT. The solution was rotary evaporated to dryness. The
solid was washed with hexane and recrystallised from CH2Cl2–
hexane to give 2a (30.0 mg, 51%) as yellow crystals. Anal. Calcd
for C25H28ClIrN2O4: C, 46.33, H, 4.35, N, 4.32. Found: C, 46.33,
It appears that in contrast to Jones’s results with DMAD,7
≡
≡
reaction of 13b with PhC CPh or PhC CH gives insertion
products that are unstable and spontaneously dissociate from the
metal without the need for prior oxidation by copper(II) salts.
However for the alkyl imines containing a functionalised side
chain which is capable of coordinating, the products of insertion of
1
H, 4.41, N, 4.25%. H NMR: d 1.31 (s, 15H, Cp*), 3.64 (s, 3H,
OMe), 3.69 (s, 3H, OMe), 6.51 (t, 1H, J 2.5, H2), 7.17 (dd, 1H, J
8.0, 1.0, H5), 7.34 (td, 1H, J 8.0, 2.0, H6), 7.43 (m, 2H, H7 H8), 7.81
(dd, 1H, J 2.5, 0.5, H3), 8.21 (dd, 1H, J 2.5, 0.5, H1).13C NMR: d
8.33 (C5Me5), 50.14 (OMe), 51.80 (OMe), 89.34 (C5Me5), 108.84
(C2), 127.29 (C5), 127.49, 128.68 (C7,8), 133.21 (C6), 134.37 (C3),
132.30, 136.88, 138.45 (C4,9,10), 145.48 (C1), 167.64, 168.08 (2 ¥
CO2Me), 176.15 (C11). ES-MS m/z 613 [M-Cl]+, MS FAB m/z
613 [M-Cl]+, 648 [M]+.
≡
PhC CPh i.e. 9a,b are stable. Pfeffer has previously commented on
the extra stability of alkyne insertion products having very electron
withdrawing substituents e.g. CO2Me.15 These results are also
consistent with Fagnou who showed that for NtBu imine Cu(II) is
not essential for isoquinoline formation.14 Notably, all of Fagnou’s
reactions involved dialkyl-substituted alkynes. We can also report
that our attempts to follow Fagnou’s reaction stoichiometrically
have failed. Acetate-asisted cyclometallation of the NtBu substi-
tuted imine with [RhCl2Cp*]2 failed to give a clean cyclometallated
product. We have noted in other cyclometallations, particularly
with rhodium that the cyclometallation reactions can be equilibria,
DFT calculations show that the process is close to thermoneutral
for rhodium.25
Preparation of 2b
A mixture of 1b (50 mg, 0.12 mmol) and DMAD (14 mg,
0.12 mmol) in MeOH (5 ml) was stirred for 5 h at RT. The
solution was rotary evaporated to dryness. The product was
washed with hexane and recrystallised from CH2CL2/hexane
to give 2b (55.0 mg, 81%) as yellow crystals. Anal. Calcd for
RhC25H28N2O4Cl: C, 53.73, H 5.05, N,5.01. Found: C 53.53, H
5.17, N 4.92%. 1H NMR: d 1.30 (s, 15H, Cp*), 3.64 (s, 3H, OMe13),
3.67 (s, 3H, OMe15), 6.50 (t, 1H, J 2.5, H2), 7.20 (dd, 1H, J 8.0,
1.0, H5), 7.36 (ddd, 1H, J 8.0, 6.0, 2.0, H6), 7.46 (m, 2H, H7 H8),
7.82 (dd, 1H, J 2.5, 0.5, H3), 8.27 (dd, 1H, J 2.5, 0.5, H1).13C
NMR (500 Mhz): 8.57 (C5Me5), 50.35 (OMe13), 51.88 (OMe15),
96.89 (d, JRhC 25, C5Me5), 108.94 (C2), 127.44 (C5), 127.68 (C6),
128.61, 133.20 (C7,8), 134.53 (C3), 130.94, 136.99, 137.10 (C4,9,10),
146.26 (C1), 166.37, 174.39 (2 ¥ CO2Me), 181.60 (d, JRhC 135, C11).
ES-MS m/z (M-Cl) 523, MS (FAB) m/z 523 [M-Cl]+
Miura has shown previously that the product of alkyne reactions
with imines catalysed by Rh depends on the substituent on
nitrogen and carbon of the imine.10 We have confirmed the
importance of the substituent on nitrogen particularly in effecting
the reductive elimination step. In addition, we have shown that
the nature of the substituents on the alkyne also play a crucial
role. The ease of cyclometallation and alkyne insertion suggests
that facilitating the reductive elimination step is key to effective
catalysis. In this regard the ability of a tBu substituted cation
to eliminate isobutene and a proton may play a crucial role in the
catalysis reported by Fagnou.14 Interestingly, for the stoichiometric
cyclometallation reaction to proceed in high yield is apparently not
a requirement for catalysis.
Preparation of 2c
A mixture of 1c (39 mg, 0.09 mmol), DMAD (16 mg, 0.13 mmol)
in MeOH (5 ml) was stirred for 3 h at room temperature, under
N2. The solution was rotary evaporated to dryness, washed with
hexane and recrystallised from CH2Cl2–hexane to give 2c (41 mg,
78%) as brown crystals. Anal. Calcd for C25H27ClN2O4Ru·CH2Cl2:
C, 48.72, H, 4.56, N, 4.37. Found: C, 49.89, H, 3.53, N, 4.13%.
1H NMR: d 1.06 (d, J 7.0, 3H, CHMeMe¢), 1.16 (d, J 7.0,
3H, CHMeMe¢), 2.11 (s, 3H, Me(Cy)), 2.64 (sept, J 7.0, 1H
CHMeMe¢), 3.63 (s, 3H, OMe), 3.64 (s, 3H, OMe), 4.12 (d, 1H,
J 5.5, Cy), 4.44 (d, 1H, J 5.5, Cy), 4.54 (d, 1H, J 5.5, Cy), 5.52
(d, 1H, J 5.5, Cy), 6.47 (t, 1H, J 2.0, H2), 7.19 (d, 1H, J 8.0, H5),
7.41 (td, 1H, J 8.0, 1.5, H6), 7.51 (m, 2H, H7, H8), 7.78 (d, 1H,
J 1.5, H3), 8.38 (d, 1H, J 1.5, H1), 13C NMR: d 18.80 (Me(Cy)),
22.64 (MeMe¢CH), 22.97 (MeMe¢CH), 30.94 (MeMe¢CH), 50.10,
51.78 (2 ¥ OMe), 80.71, 82.40, 83.07, 92.81 (4 ¥ CH, Cy), 102.84
(Cq, Cy), 108.35 (C3), 109.37 (Cq, Cy), 126.38 (C5), 127.45 (C6),
128.54, 132.90 (C7,8), 134.22 (C2), 130.66, 137.41, 139.68 (C4,9,10),
145.25 (C1), 164.69, 175.47 (2 ¥ CO2Me), 190.94 (C11). ES-MS
m/z 521 [M-Cl]+, FAB MS m/z 556 [M]+, 521 [M-Cl]+.
Experimental
The reactions described were carried out under nitrogen using dry
solvents; however, once isolated as pure solids the compounds can
be handled in air. 1H, and 13C-{ H} NMR spectra were obtained
1
using Bruker 300, 400 or 500 MHz spectrometers, with CDCl3
as solvent, unless otherwise stated. Chemical shifts were recorded
in ppm (with tetramethylsilane as internal reference). FAB mass
spectra were obtained on a Kratos concept mass spectrometer
using NOBA as matrix. The electrospray (ES) mass spectra were
recorded using a micromass Quattra LC mass spectrometer with
dichloromethane or methanol as solvent. Infrared spectra were run
as solids in a diamond ATR cell using a Perkin Elmer Spectrum
1 instrument. Microanalyses were performed by the Elemental
Analysis Service (University of North London). All starting
materials were obtained from Aldrich, with the exception of
[MCl2Cp*]2 (M = Rh, Ir)26 and [RuCl2(p-cymene)]2,27 complexes
This journal is
The Royal Society of Chemistry 2010
Dalton Trans., 2010, 39, 10447–10457 | 10453
©

Preparation of 3a
or C10), 183.19 (C11). ES-MS (ESI) m/z 557 [M-Cl]+, MS (FAB)
m/z 557 [M-Cl]+
≡
A mixture of 1a (50 mg, 0.10 mmol) and PhC CPh (19 mg,
0.11 mmol) in MeOH (5 ml) was stirred for 3 h at RT. The solution
was rotary evaporated to dryness. The product was washed with
hexane and recrystallised from CH2Cl2–hexane to give 3a (42 mg,
62%) as yellow crystals. Anal. Calcd for C33H32ClIrN2·CHCl3: C,
Preparation of 4b
≡
A mixture of 1b (66 mg, 0.16 mmol) and PhC CH (18 mg,
0.17 mmol) in MeOH (7 ml) was stirred at room temperature
for 2 h. The solution was rotary evaporated to dryness. The solid
was dissolved in CH2Cl2 and filtered through Celite. The filtrate
was evaporated to dryness and the crude product was purified by
passing through a short silica column, using CH2Cl2 as the first
eluent and MeOH–CH2Cl2 (1 : 9) as the second eluent. The second
fraction was rotary evaporated to dryness to give 4b (30 mg, 36%)
as an orange solid. Anal. Calcd for C27H28ClN2Rh: C 62.50, H
5.44, N 5.40. Found: C 62.58, H 5.34, N 5.36%. 1H NMR: d 1.30
(s, 15H, Cp*), 6.48 (t, 1H, J 2.5, H2), 7.05 (m, 1H, H15), 7.07 (s,
1H, H10), 7.15 (m, 4H, H13 H14), 7.24 (m, 2H, H5, H6), 7.39 (ddd,
1H, J 8.0, 6.0, 2.0, H7) 7.46 (dt, 1H, J 8.0, 1.0, H8), 7.76 (dd, 1H, J
2.5, 1.0, H3), 8.46 (dd, 1H, J 2.5, 1.0, H1).13C NMR: 9.21 (C5Me5),
95.82 (d, JRhC 25, C5Me5), 108.41 (C2), 124.77 (C15), 125.57, 126.17
(C5,6), 126.68, 126.88 (C13,14), 128.10 (C7), 128.35 (C10), 132.81 (C8),
134.26 (C3), 135.27, 138.38, 152.85 (Cq, C4 C9 C12), 145.48 (C1),
178.64 (d, JRhC 125, C11). ES-MS m/z 483 [M-Cl]+
1
50.81, H, 4.14, N, 3.49. Found: C, 50.81, H, 4.28, N, 3.40%. H
NMR: d 1.36 (s, 15H, Cp*), 6.56 (t, 1H, J 2.5, H2), 6.67 (t, 1H,
J 7.0, Ph), 6.71 (dd, 2H, J 8.0, 1.5, Ph), 6.83 (tt, 1H, J 7.5, 1.5,
Ph), 6.91 (td, 2H, J 7.0, 1.0, Ph), 7.18 (m, 1H, Ph), 7.20 (t, 1H, J
2.0, Ph), 7.22 (d, 1H, J 1.0, Ph), 7.24 (dd, 1H, J 5.0, 5.5, Ph), 7.26
(t, 1H, J 2.5, Ph), 7.34 (m, 2H, Ph), 7.52 (m, 1H, Ph), 7.91 (dd, J
2.5, 1.0, 1H, H3), 8.41 (dd, J 2.5, 1.0, 1H, H1). 13C NMR: d 8.79
(C5Me5), 88.46 (C18), 108.36 (C2), 122.79, 124.34, 125.43, 126.51,
126.64, 131.60, 131.80 (CH, Ph), 133.77 (C3), 134.45 (CH, Ph),
136.82, 138.54 (Ar Cq or C10), 144.62 (C1), 145.19, 147.65, 154.22,
(Ar Cq or C10), 161.23 (C11). ES-MS m/z 647 [M-Cl]+, MS FAB
m/z 647 [M-Cl]+, 684 [M]+
Preparation of 3b
≡
A mixture of 1b (70 mg, 0.17 mmol) and PhC CPh (33 mg,
0.18 mmol) in MeOH (7 ml) was stirred at room temperature
for 3 h. The solution was rotary evaporated to dryness and the
solid was dissolved in CH2Cl2 and filtered through Celite. The
filtrate was evaporated to dryness and the solid was washed with
hexane to give 3b (80 mg, 81%) as an orange solid. Anal. Calcd
for C33H32ClN2Rh: 66.62, H 5.42, N 4.71. Found: C 66.53, H 5.41,
N 4.79%. 1H NMR: d 1.35 (s, 15H, Cp*), 6.56 (t, 1H, J 2.5, H2),
6.72 (m, 4H, Ph), 6.85 (m, 2H, Ph), 6.92 (m, 3H, Ph), 7.25 (m,
Preparation of 7a
KPF6 (48 mg, 0.26 mmol) was added to a solution of 5a (70 mg,
0.13 mmol), in acetonitrile (10 ml). The mixture was stirred
overnight, then filtered through Celite to remove excess KPF6.
The filtrate was evaporated to dryness and washed with hexane to
give 7a as a brown solid (70 mg, 78%) which could be recrystallised
from dichloromethane–hexane. Anal.Calcd for C22H30F6N2OIrP:
C, 39.11, H, 4.48, N, 4.15. Found: C, 38.95, H, 4.69, N, 3.97%.
1H NMR: d 1.75 (s, 15H, Cp*), 2.36 (s, 3H, NCMe), 3.34 (s, 3H,
OMe), 3.66 (m, 1H, CHHO), 3.84 (dt, 1H, J 10, 2.5, CHHO), 4.17
(m, 2H, NCH2), 7.11 (t, 1H, J 7.5, H4), 7.22 (dt, 1H, J 7.5, 1, H5),
5H, Ph), 7.92 (dd, 1H, J 3, 0.5, H3), 8.56 (dd, 1H, J 2, 1, H1). 13
C
NMR: d 9.07 (C5Me5), 96.09 (d, JRhC 6.5, C5Me5), 108.40 (C2),
123.10, 124.55, 125.92, 126.57, 127.01, 128.40, 131.13 (CH, Ph),
133.77 (C3), 134.54 (CH, Ph), 136.89, 137.04, 143.25 (Ar Cq or
C10), 145.78 (C1), 146.71, 152.66 (ArCq or C10), 176.08 (d, JRhC
30.5, C11). ES-MS: m/z 559 [M-Cl]+. MS FAB: m/z 594 [M]+, 559
[M-Cl]+.
3
6
=
7.60 (d, 1H, J 7.5, H ), 7.69 (d, 1H, J 7, H ), 8.40 (s, 1H, HC N).
13C NMR: d 3.71 (NCMe), 9.10 (C5Me5), 58.88 (OMe), 61.65
(CH2O), 69.50 (NCH2), 91.52 (C5Me5), 119.16 (NCMe), 123.87,
Preparation of 3c
129.52, 132.69, 134.65 (C3, C4, C5, C6), 146.92 (C2), 162.29 (C1Ir),
179.28 (HC N). MS (FAB): m/z 490 [M-NCMe] . IR: n(C N)
+
≡
=
=
A mixture of 1c (50 mg, 0.12 mmol) and PhC CPh (23 mg,
0.13 mmol) in MeOH (5 ml) was stirred for 1 h at RT. The solution
was rotary evaporated to dryness. The product was washed with
hexane and recrystallised from CH2Cl2–hexane to give 3c (30 mg,
42%) as brown crystals. Anal. Calcd for C33H31ClN2Ru: C, 66.94,
1606 cm-1.
Preparation of 7b
1
H, 5.28, N, 4.73. Found: C, 66.95, H, 5.34, N, 4.65%. H NMR:
KPF6 (113 mg, 0.61 mmol) was added to a solution of 5b (134 mg,
0.31 mmol), in acetonitrile (10 ml). The mixture was stirred
overnight, then filtered through Celite to remove excess KPF6.
The filtrate was evaporated to dryness and washed with hexane
to give 7b as a yellow solid (181 mg, 86%). Anal. Calcd for
C22H30F6N2OPRh: C, 45.06, H, 5.16, N, 4.78. Found: C, 45.14,
d 1.08 (d, J 7.0, 3H, CHMeMe¢), 1.23 (d, J 7.0, 3 H, CHMeMe¢),
2.44 (s, 3H, Me, Cy), 2.79 (sept, 1H, J 7.0, CHMeMe¢), 3.48 (dd,
1H, J 6.0, 1.0, Cy), 4.49 (dd, 1H, J 6.0, 1.0, Cy), 4.63 (dd, 1H,
J 6.0, 1.0, Cy), 5.54 (dd, 1H, J 6.0, 1.0, Cy), 6.50 (t, 1H, J 2.5,
H2), 6.75 (m, 4H, Ph), 6.86 (tt, 1H, J 7.0, 1.5, Ph), 6.93 (tm, 3H, J
7.0, Ph), 7.22 (dt, 1H, J 7.0, 1.0, H8), 7.26 (m, 1H, H6,7), 7.29 (m,
1H, H6,7), 7.30 (m, 2H, Ph), 7.34 (m, 1H, H5), 7.85 (dd, 1H, J 2.5,
1.0, H3), 8.57 (dd, 1H, J 2.5, 1, H1) 13C NMR d 19.48 (Me, Cy),
23.04 (MeMe¢CH), 23.46 (MeMe¢CH), 31.21 (MeMe¢CH), 75.14,
78.71, 80.91, 96.25 (4 ¥ CH, Cy), 103.65 (Cq, Cy), 107.69 (C2),
110.22 (Cq, Cy), 122.99, 124.53, 125.36, 125.76, 126.19, 127.04,
128.00, 128.34, 131.41 (CH, Ph), 133.24 (C3), 133.55 (C5), 137.40,
137.57 (Cq, Ar or C10), 143.98 (C1), 145.90, 146.62, 152.32 (Cq, Ar
1
H, 5.21, N, 4.55%. H NMR: d 1.70 (s, 15H, Cp*), 2.23 (s, 3H,
NCMe), 3.36 (s, 3H, OMe), 3.74 (m, 1H, CHH¢O), 3.90 (dt, 1H,
J 10, 3, CHH¢O), 4.01 (m, 1H, NCHH¢), 4.16 (m, 1H, NCHH¢),
7.16 (dt, 1H, J 7.5, 1, H4), 7.31 (dt, 1H, J 7.5, 1.5, H5), 7.52
(dd, 1H, J 7.5, 1.5, H3), 7.72 (d, 1H, J 7.5, H6), 8.24 (d, 1H,
JRhH 4, HC N). 13C NMR: d 3.54 (NCMe), 9.42 (C5Me5), 58.91
=
(OMe), 60.43 (CH2O), 69.85 (NCH2), 98.29 (d, JRhC 7, C5Me5),
124.44, 129.43, 131.96, 135.51 (C3, C4, C5, C6), 145.96 (C2), 176.37
10454 | Dalton Trans., 2010, 39, 10447–10457
This journal is
The Royal Society of Chemistry 2010
©

1
+
=
(HC N), C Rh (not observed). MS (FAB): m/z 400 [M-NCMe] .
and then the solvent exchanged by NCMe and refluxed for 18 h.
The solution was evaporated to dryness and washed with hexane
to give a light brown hexane soluble from which 10 was isolated as
an orange solid (24 mg, 50%), Anal. Calcd for C27H21N: C, 90.21,
H, 5.89, N, 3.90. Found: C, 90.03, H, 5.81, N, 3.80%. 1H NMR: d
3.90 (br, 1H NH), 5.65 (s, 1H, CH), 6.45 (d, 1H, J 7, Ph), 6.69 (m,
3H, Ph) 6.90 (m, 1H, Ph) 6.93 (d, 2H, J 7, Ph), 7.1–7.6 (m, 12H,
Ph). MS (FAB): m/z 358 [M]+.
-1
=
IR: n(C N) 1614 cm .
Preparation of 8a
A mixture of 6a (130 mg, 0.24 mmol), KPF6 (130 mg, 0.71 mmol)
in acetonitrile (10 ml); was stirred for 24 h, then filtered through
Celite to remove excess KPF6. The filtrate was evaporated to
dryness and washed with hexane to give to give 8a (120 mg, 72%)
as an orange precipitate. Anal. Calcd for C25H28F6IrN2P·CH2Cl2:
C, 40.10, H, 3.85, N, 3.60. Found: C, 39.57, H, 3.10, N, 3.03%. 1H
NMR: d 1.51 (s, 15H, Cp*), 2.49 (s, 3H, NCMe), 7.19 (dt, 1H, J
7.5, 1, H4), 7.30 (dt, 1H, J 7.5, 1.5, H5), 7.40 (m, 3H, Ph), 7.56
(m, 2H, Ph), 7.73 (dd, 1H, J 7.5, 1, H3), 7.80 (d, 1H, J 7.5, H6),
Preparation of 11a
≡
PhC CH (30 mg, 0.30 mmol) was added to solution of 7a (100 mg,
0.15 mmol) in dichloromethane; after stirring for 30 h, 11a was
isolated as a yellow precipitate (105 mg, 85%). Anal. Calcd for
C36H39F6IrNOP: C, 51.54, H, 4.69, N, 1.67. Found: C, 51.22, H,
8.42 (s, 1H, HC N). 13C NMR: d 3.72 (NCMe), 8.61 (C5Me5),
=
1
91.93 (C5Me5), 120.06 (NCMe), 122.31, 124.07, 128.58, 130.11,
4.59, N, 1.59%. H NMR: d 1.69 (s, 15H, Cp*), 3.06 (m, 2H,
130.82, 133.61, 135.00 (C3, C4, C5, C6 and Ph), 147.42 (C2), 149.83
CH2O), 3.14 (s, 3H, OMe), 3.93 (m, 1H, NCHH¢), 4.13 (m, 1H,
1
+
(Ph), 163.67 (C Ir), 178.13 (HC N). MS (FAB): m/z 549 [M] ,
508 [M-NCMe] . IR: n(C N) 1583 cm .
NCHH¢), 6.06 (s, 1H, H7), 6.72 (s, 1H, H10), 7.46 (m, 8H, H4, H5,
=
+
-1
(2 ¥ Ph, Hm, Hp)), 7.73 (m, 5H, H3, (2 ¥ Ph, Ho)), 8.04 (d, 1H,
=
6
J 8, H ), 8.09 (s, 1H, HC N). 13C NMR: d 9.05 (C5Me5), 48.95
=
(C7), 53.65 (Cq), 58.65 (OMe), 70.72 (CH2O), 71.73 (NCH2), 80.18
(Cq), 99.07 (C5Me5), 121.18 (C10), 127.57, 127.81, 129.00, 129.30,
130.06, 130.23, 131.17, 135.53, 136.34 (CH, Ph), 128.09, 129.20,
Preparation of 9a
≡
PhC CPh (11 mg, 0.06 mmol) was added to solution of 7a (40 mg,
0.06 mmol) in dichloromethane (5 ml); after stirring for 30 h,
the solution was evaporated to dryness and then washed with
hexane to give 9a as a yellow precipitate (40 mg, 83%). Anal.
Calcd for C34H37F6IrNOP: C, 50.24, H, 4.59, N, 1.72. Found: C,
50.00, H, 4.47, N, 1.64%. 1H NMR: d 1.39 (s, 15H, Cp*), 2.48 (s,
3H, OMe), 3.21 (m, 1H, CHH¢O), 3.32 (m, 1H, CHH¢O), 4.13
(m, 2H, NCH2), 6.72 (m, 2H, Ph), 6.97 (m, 6H, H4, H5, Ph),
7.29 (m, 5H, H , Ph), 7.59 (m, 1H, H ), 9.14 (s, 1H, HC N). 13C
NMR: d 9.04 (C5Me5), 61.53 (OMe), 65.51 (CH2O), 73.14 (NCH2),
89.18 (C9), 99.07 (C5Me5), 125.45, 126.37, 127.52, 128.63, 131.37,
=
133.39, 135.18, 150.17 (all Cq), 167.90 (HC N). MS (FAB): m/z
+
-1
=
694 [M] . IR: n(C N) 1615 cm .
Preparation of 12a
≡
PhC CH (34 mg, 0.33 mmol) and KPF6 (76 mg, 0.41 mmol)
were added to solution of 6a (90 mg, 0.17 mmol) in NCMe; after
stirring for 7 h, NCMe was replaced by dichloromethane and the
solution stirred for a further 21 h. After this time the solvent was
evaporated and the solid was washed through a small plug of silica
(CH2Cl2/NCMe). The solvent was evaporated to give 12a as a red
precipitate (92 mg, 65%). Anal. Calcd for C36H37F6IrNP: C, 54.66,
6
3
=
131.94, 132.26, 132.10, 134.13 (Ar–H), 141.86, 144.65, 145.65,
149.49, 158.93 (Ph Cq and C ), 170.84 (HC N). MS (FAB): m/z
668 [M] . IR: n(C N) 1595 cm .
7,8
=
+
-1
1
=
H, 4.35, N, 1.63. Found: C, 54.51, H, 4.23, N, 1.53%. H NMR
(in d4-MeOH): d 1.51 (s, 15H, Cp*), 5.20 (s, 1H, H7), 6.72 (s, 1H,
H10), 6.89 (m, 2H, 2 ¥ Ph), 7.01 (m, 3H, H4, 2 ¥ Ph), 7.20 (m, 4H,
H6, 2 ¥ Ph), 7.54 (m, 8H, Ph), 7.92 (dt, 1H, J 7.5, 1.5, H5), 8.02
Preparation of 9b
≡
3
+
PhC CPh (5.2 mg, 0.03 mmol) was added to solution of 5b (16 mg,
=
(d, 1H, J 7.5, H ), 8.18 (s, 1H, HC N). MS (FAB): m/z 712 [M] .
-1
0.03 mmol) in CDCl3 in an NMR tube, after 30 h, the solution was
evaporated to dryness and then washed with hexane to give 7b as
a yellow precipitate (18 mg, 85%). 1H NMR: d 1.36 (s, 15H, Cp*),
2.35 (s, 3H, OMe), 3.04 (m, 1H, CHH¢O), 3.43 (m, 1H, CHH¢O),
4.05 (m, 1H, NCHH¢), 4.23 (m, 1H, NCHH¢), 6.75 (m, 2H, Ph),
=
IR: n(C N) 1615 cm .
Preparation of 14b
≡
PhC CH (10 mgs, 0.09 mmol) was added to a solution of complex
6.95 (m, 4H, H4, H5, Ph), 7.08 (m, 1H, Ph), 7.33 (m, 5H, H6, Ph),
13b (50 mgs, 0.13 mmol) in MeOH (5 mL). The reaction was
monitored by ESI, and after 5 min showed mostly m/z 458 (mono
insertion), and traces of 13b. Over a period of 30 min an orange
precipitate formed which was collected by filtration (12 mgs, 19%).
1H NMR: d 1.35 (s, 15H, Cp*), 3.89 (s, 3H, Me), 7.11 (m, 2H, Ph),
7.22 (m, 6H, Ph), 7.32 (d, 1H, J 7.5, H6), 7.40 (dd, 1H, J 6.0, 7.0,
H3), 8.63 (s, 1H, NCH)
3
=
7.53 (m, 1H, Ph), 7.64 (m, 1H, H ), 9.14 (d, 1H, J 3, HC N). MS
(FAB): m/z 578 [M] . IR: n(C N) 1596 cm .
+
-1
=
Preparation of 10
≡
From 8a: PhC CPh (51.4 mg, 0.29 mmol) was added to solution
of 8a (100 mg, 0.14 mmol) in dichloromethane and refluxed for
20 h. After this time the solution was evaporated to dryness washed
with hexane to give a light brown hexane soluble and a deep brown
insoluble fraction. The latter was washed through silica, however,
no pure fraction could be isolated. Compound 10 was isolated
from the hexane soluble fraction as an orange solid (23 mg, 45%).
X-ray crystal structure determinations
Details of the structure determinations of crystals of 2a–c, 3a, 7b,
8a, 9a, 10, 11a, and 14b are given in Tables 1 and 2 (Complexes
3b,c are included in the supplementary material‡). Data were
collected on a Bruker Apex 2000 CCD diffractometer using
≡
From 6b: PhC CPh (23.7 mg, 0.13 mmol) was added to solution
˚
of 6b (60 mg, 0.13 mmol) in dichloromethane was stirred for 8 h
graphite monochromated Mo-Ka radiation, l = 0.7107 A at
This journal is
The Royal Society of Chemistry 2010
Dalton Trans., 2010, 39, 10447–10457 | 10455
©

Table 1 Crystallographic data for 2a–c, 3a and 7b
2a
2b
2c
3a
7b
Empirical formula
Formula weight
Temperature
C25H28ClIrN2O4
648.14
150(2) K
Monoclinic
P21/n
10.0222(18)
16.342(3)
15.312(3)
90
106.030(3)
90
2410.4(8)
4
1.786
C25H28ClN2O4Rh
558.85
150(2) K
Monoclinic
P21/n
10.0361(17)
16.349(3)
15.289(3)
C26H29Cl3N2O4Ru
640.93
150(2) K
Triclinic
¯
P1
9.240(6)
9.619(6)
16.215(11)
91.764(11)
103.811(11)
108.957(11)
1314.4(15)
2
1.619
0.937
652
C34H33Cl4IrN2
803.62
150(2) K
Monoclinic
P21/n
12.990(2)
15.877(3)
15.564(3)
C22H30F6N2OPRh
586.36
150(2) K
Orthorhombic
Pbca
11.7650(5)
17.6433(7)
24.0030(9)
90
90
90
4982.4(3)
8
1.563
0.811
2384
Crystal system
Space group
˚
a/A
˚
b/A
˚
c/A
a/◦
b/◦
g/◦
U/A
Z
106.251(3)
99.493(3)
3
˚
2408.4(7)
4
1.541
0.854
3166.0(9)
4
1.686
4.582
Density (calc.) Mg m-3
m/mm-1
5.684
1272
F(000)
1144
1584
Crystal size mm
Theta range
Index ranges
0.11 ¥ 0.10 ¥ 0.07
1.86 to 26.99
-12 ≤ h ≤ 12,
-20 ≤ k ≤ 20,
-19 ≤ l ≤ 19
19930
0.22 ¥ 0.19 ¥ 0.07
1.86 to 26.99
-12 ≤ h ≤ 12,
-20 ≤ k ≤ 20,
-19 ≤ l ≤ 19
19939
0.24 ¥ 0.17 ¥ 0.05
2.25 to 26.00
-11 ≤ h ≤ 11,
-11 ≤ k ≤ 11,
-19 ≤ l ≤ 19
10350
0.25 ¥ 0.16 ¥ 0.05
1.85 to 26.00
-15 ≤ h ≤ 16,
-19 ≤ k ≤ 19,
-18 ≤ l ≤ 19
24390
0.25 ¥ 0.23 ¥ 0.17
1.70 to 25.00
-13 ≤ h ≤ 13,
-20 ≤ k ≤ 20,
-28 ≤ l ≤ 28
34225
Reflections collected
Independent reflections (Rint
Data/restraints/parameters
Goodness-of-fit, F2
)
5258 [Rint = 0.0758]
5258/0/304
0.916
R1 = 0.0358,
wR2 = 0.0591
R1 = 0.0488,
wR2 = 0.0625
1.620 and -1.507
5252 [Rint = 0.0606]
5252/0/305
0.974
R1 = 0.0357,
wR2 = 0.0715
R1 = 0.0473,
wR2 = 0.0750
0.627 and -0.561
5086 [Rint = 0.0757]
5086/0/330
0.992
R1 = 0.0561,
wR2 = 0.1283
R1 = 0.0686,
wR2 = 0.1340
1.262 and -1.09
6211 [Rint = 0.0956]
6211/0/375
0.899
R1 = 0.0419,
wR2 = 0.0714
R1 = 0.0648,
wR2 = 0.0770
1.447 and -1.283
4377 [Rint = 0.0331]
4377/0/305
1.073
R1 = 0.0353,
wR2 = 0.0882
R1 = 0.0392,
wR2 = 0.0903
1.041 and -0.715
Final R indices [I > 2s(I)]
R indices (all data)
-3
˚
Largest diff. peak and hole/e A
Table 2 Crystallographic data for 8a, 9a, 10, 11a, 14b
8a
9a
10
11a
14b
Empirical formula
Formula weight
Temperature
C25H28F6IrN2P
693.66
150(2) K
Orthorhombic
P21/n
8.6691(4)
27.6056(12)
11.2039(5)
90
110.8060(10)
90
2506.42(19)
4
1.838
C34.5H38ClF6IrNOP
855.28
290(2) K
Tetragonal
P-42(1)c
21.2244(8)
21.2244(8)
15.9689(8)
90
90
90
7193.6(5)
8
1.579
C27H21N
359.45
150(2) K
Monoclinic
P21/c
10.669(5)
8.067(4)
22.852(11)
90
102.836(9)
90
1917.6(16)
4
1.245
0.072
760
C37H40Cl2F6IrNOP
922.77
150(2) K
Monoclinic
P21/c
11.807(6)
14.582(8)
21.324(12)
90
C26H29ClNRh
493.86
150(2) K
Orthorhombic
Pbca
13.159(4)
14.219(4)
23.675(7)
90
90
90
4430(2)
8
Crystal system
Space group
˚
a/A
˚
b/A
˚
c/A
a/◦
b/◦
g/◦
U/A
Z
95.270(9)
90
3656(3)
3
˚
4
Density (calc.) Mg m-3
m/mm-1
1.677
3.904
1828
1.481
5.452
1352
3.889
3384
0.904 mm-1
2032
F(000)
Crystal size mm
Theta range
Index ranges
0.20 ¥ 0.17 ¥ 0.06
1.48 to 27.00
-11 ≤ h ≤ 11,
-35 ≤ k ≤ 34,
-14 ≤ l ≤ 14
21132
0.39 ¥ 0.09 ¥ 0.09
1.36 to 27.00
-27 ≤ h ≤ 27,
-27 ≤ k ≤ 26,
-20 ≤ l ≤ 20
60010
0.19 ¥ 0.13 ¥ 0.05
1.83 to 25.00
-12 ≤ h ≤ 12,
-9 ≤ k ≤ 9,
-27 ≤ l ≤ 27
13317
0.26 ¥ 0.17 ¥ 0.08
1.69 to 26.00
-14 ≤ h ≤ 14,
-17 ≤ k ≤ 17,
-25 ≤ l ≤ 26
27890
0.24 ¥ 0.07 ¥ 0.03
1.72 to 26.00
-16 ≤ h ≤ 16,
-17 ≤ k ≤ 17,
-29 ≤ l ≤ 28
32847
Reflections collected
Independent reflections (Rint
Data/restraints/parameters
Goodness-of-fit, F2
)
5464 [Rint = 0.0290]
5464/0/376
0.999
R1 = 0.0230,
wR2 = 0.0551
R1 = 0.0269,
wR2 = 0.0563
0.995 and -0.501
7840 [Rint = 0.0796]
7840/0/398
0.804
R1 = 0.0403,
wR2 = 0.0691
R1 = 0.0727,
wR2 = 0.0756
1.030 and -0.412
3379 [Rint = 0.1222]
3379/0/254
0.870
R1 = 0.0654,
wR2 = 0.1331
R1 = 0.1560,
wR2 = 0.1649
0.376 and -0.198
7169 [Rint = 0.0638]
7169/0/448
0.974
R1 = 0.0340,
wR2 = 0.0773
R1 = 0.0439,
wR2 = 0.0817
1.407 and -0.861
4347 [Rint = 0.2825]
4347/0/268
0.934
R1 = 0.0723,
wR2 = 0.1073
R1 = 0.1518,
wR2 = 0.1266
0.806 and -1.307
Final R indices [I > 2s(I)]
R indices (all data)
-3
˚
Largest diff. peak and hole/e A
10456 | Dalton Trans., 2010, 39, 10447–10457
This journal is
The Royal Society of Chemistry 2010
©

150 K. The data were corrected for Lorentz and polarisation
effects and empirical absorption corrections (SADABS).28 were
applied in all cases. The structures were solved by Patterson
methods and refined by full-matrix least squares on F2 using the
program SHELXTL.29 All hydrogen atoms bonded to carbon were
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200–205; G. Dyker, ed., Handbook of C–H transformations, Wiley-
VCH, Weinheim, 2005.
10 T. Fukutani, N. Umeda, K. Hirano, T. Satoh and M. Miura, Chem.
˚
included in calculated positions (C–H = 0.96 A) using a riding
Commun., 2009, 5141–5143.
model. All non-hydrogen atoms were refined with anisotropic
displacement parameters without positional restraints. Figures
were drawn using the program ORTEP.30
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Acknowledgements
We thank the Saudi Arabian government (O. A-D) for a stu-
dentship, the EPSRC for financial support (YB), Professor S. A.
Macgregor (Heriot Watt) for discussions, and Johnson Matthey
for a loan of platinum metal salts.
12 N. Umeda, H. Tsurugi, T. Satoh and M. Miura, Angew. Chem., Int.
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